[{"type":"speech","title":"Surface velocity of shear quartzes for high speed friction measurements","issued":{"date-parts":[["2008"]]},"author":[{"family":"Zhang","given":"F."},{"family":"Marti","given":"O."},{"family":"Walheim","given":"S."},{"family":"Schimmel","given":"T."}],"note":"72.Jahrestagung der Deutschen Physikalischen Gesellschaft und DPG Fr\u00fchjahrstagung des Arbeitskreises Festk\u00f6rperphysik, Fachverband Oberfl\u00e4chenphysik, Berlin, 25.-29.Februar 2008 Verhandlungen der Deutschen Physikalischen Gesellschaft, R.6, B.43(2008) O 43.22","abstract":"Surface Science Division (O)\nTuesday\nperimentation in both scanning tunneling microscopy (STM) and noncontact atomic force microscopy (NC-AFM) modes. An exchangeable\ntuning fork based Q-plus style sensor is used to allow for \ufb02exibility in\nchoosing probe tip materials. The system features an on-top cryostat,\nwhere the microscope is enclosed in a double set of thermal shields.\nTip as well as sample can be changed in-situ at low temperatures to\nkeep turn-around times low. By opening the front shutters of the\nshields, unrestricted access from dedicated \ufb02anges permits the direct\ndeposition of molecules or atoms on either tip or sample while they remain cold. As examples for the microscope\u2019s performance, we present\ndata measured on Cu(111) in STM mode as well as on graphite in\nNC-AFM mode, featuring atomic resolution with corrugations of 45 pm and corrugations below 1 pm could be measured. In addition,\natomic resolution data obtained by means of three-dimensional force\nspectroscopy is shown.\nO 43.21\nTue 18:30\nPoster F\nEnergy dissipation of ballistic injected electrons and holes\nthrough individual molecules \u2014 \u2022Alexander Bernhart1 ,\n\u00a8\nBobisch2 , and Rolf Moller1 \u2014 1 Department of Physics, University of Duisburg-Essen, 47048 Duisburg, Germany \u2014 2 University of\nCalifornia, Irvine, USA\nBallistic Electron Emission Microscopy (BEEM) not only represents an\nideal technique to study the electronic transmission at the Schottkyinterface between a metal and a semiconductor, but moreover it allows\nto analyze the ballistic transport through adsorbates on top of a metal.\nBismuth (Bi) \ufb01lms with a thickness of 3-4nm were grown on n-doped\nand p-doped Si(100) and Si(111). Recently we could analyze the ballistic transport of electrons through two di\ufb00erent molecular adlayers,\nPTCDA and C60 , deposited on top of the Bi \ufb01lm. In addition the\nballistic transport of holes through an adlayer of C60 was studied. All\nexperiments were performed by a modi\ufb01ed \u201dNanoprobe\u201dsystem (Omicron) providing four STM units which may be operated independently\non the same sample. In this case one STM unit was used to contact\nthe metal layer, and other one is operated as a conventional STM at\nnegative or positive tip bias, hence injecting electrons or holes into the\nsample surface.\nO 43.22\nTue 18:30\nPoster F\nmeasurements \u2014 \u2022fengzhen zhang1 , othmar marti1 , stefan\nwalheim2 , and thomas schimmel2 \u2014 1 Uni Ulm \u2014 2 Uni Karlsruhe\/FZK\nInvestigations of the friction properties with the relative low\nspeeds(micrometer\/s) have been carried out with Atomic Force Microscopy(AFM). Technologically relevant friction processes operate at\nspeeds of several m\/s. Due to the limitation of the piezo scanners in\nstandard AFM, a new oscillation setup is required for the microscopic\nresearch on high speed friction. We have measured the surface velocity\nof shear quartzes. In this presentation we show the calibration setup\nand results of the surface speed for 3MHz quartzes. We discuss the\nin\ufb02uence of surface inhomogeneities on the accuracy of the velocity\nmeasurement. As a \ufb01rst application we present friction measurements\nobtained on structured \ufb01lms deposited on shear quartzes.\nO 43.23\nTue 18:30\nPoster F\nScanning tunneling microscopy measurements of graphene on\nan insulating substrate. \u2014 \u2022Viktor Geringer1 , Sven Runte1 ,\n\u00a8\nWe present scanning tunneling microscopy (STM) measurements of\nsingle and few layer graphene examined under ultrahigh vacuum conditions. The samples were prepared on a silicon dioxide surface by mechanical exfoliation of a graphite crystal and contacted by depositing\ngold electrodes around the graphene \ufb02ake. An instrumental challenge\nin STM investigations of small graphene \ufb02akes is the tip positioning\nwith respect to the sample. We solved this technical problem by using\nan optical long-distance microscope and a x-y-positioning drive for the\nSTM sample stage. A lateral pre-positioning precision of 5-10 \u00b5m has\nbeen achieved.\nWe show atomically resolved and large-scale topographic images of\nthe graphene surface as well as \ufb01rst scanning tunneling spectroscopy\n(STS) results.\nO 43.24\nTue 18:30\nPoster F\nA UHV-STM system for measurements at 300 mK and 14 T\n\u2014 \u2022Stefan Becker, Marcus Liebmann, and Markus Morgenstern\nWe have designed an ultrahigh vacuum (UHV) system featuring a\nhomebuilt scanning tunnelling microscope (STM) inside of a 300 mK\ncryostat with a 14 T solenoid magnet exhibiting a single-shot time of\n100 h. Two independent chambers hold various instruments for sample and STM tip preparation, including sample heaters, a sputter gun,\nevaporators and a combined LEED\/Auger system. The STM body\nis compact and rigid (\u00d8 30 mm) for stability and high resonance frequencies. It has an in situ tip exchange mechanism and a sample\npositioning stage. The whole system is supported by air damping legs\ninside an acoustically insulating room.\nO 43.25\nTue 18:30\nPoster F\nDevelopment of TERS System with Scanning Capability \u2014\nThe combination of Tip-Enhanced Raman Spectroscopy with real-time\nsurface characterization in one experimental setup shows great promise\nas a method for precise local measurement of spatially con\ufb01ned systems. After employing an AFM with an etched [1] nano-apex scanning\ntip made of Ag or Au[2] to gain structural information one can immediately use the same tip to substantially increase Raman activity at a\nparticular point of interest. Single molecules trapped near the surface\nof nano-porous oxidized silicon and alumina can be investigated using\nthis \ufb01nely tunable, highly directed approach.\nO 43.26\nTue 18:30\nPoster F\nUse of a \u201cneedle-sensor\u201d for non-contact scanning force\nmicroscopy and simultaneous measurement of the tunnel\u00a8\ning current \u2014 Bert Voigtlander1 and \u2022Irek Morawski1,2 \u2014\n1 Institute of Bio- and Nanosystems (IBN 3), and cni \u2013 Center of Nanoelectronic Systems for Information Technology, Research Centre J\u00a8 lich,\n52425 J\u00a8 lich, Germany \u2014 2 Institute of Experimental Physics, Univeru\nsity of Wroclaw, pl. Maxa Borna 9, PL 50-204 Wroclaw, Poland\nA simultaneous measurement of forces and tunneling current during\nimaging of surfaces is of great interest. We present AFM\/STM images\nof graphite and metal surface obtained by means of the quartz needlesensor with an attached tungsten tip at ambient conditions. The needle\nsensor is an extensional mode quartz oscillator operating at a frequency\nof 1 MHz and one is similar to a tuning fork sensor more frequently\nused in scanning force microscopy. This sensor has been operated with\na phase locked loop (PLL) control extended with an additional electronic circuit, namely an attenuator, two band-pass ampli\ufb01er stages,\nproviding both: sub-angstroms mechanical oscillation amplitude and\nhigh signal\/noise ratio. Dependences of the frequency shift against\na tip-surface displacement measured for mentioned surfaces are presented. A \u201dfeedback circuit enabled\u201dmethod of a calibration of the\nneedle-sensor vibration amplitude is proposed and discussed.\nO 43.27\nTue 18:30\nPoster F\nConstruction of a Fibre-Tip SNOM for Investigation of\nSoft Organic Materials \u2014 \u2022Philipp Lange2 , Omar Al-Khatib1 ,\n\u00a8\n\u00a8\n\u00a8\nDorthe M. Eisele1 , Mario Dahne2 , Jurgen P. Rabe1 , and Stefan\nKirstein1 \u2014 1 HU-Berlin, Institut f\u00a8r Physik, Newtonstr. 15, 12489\nBerlin\nThe setup of a \ufb01bre-tip scanning near \ufb01eld optical microscope (SNOM)\nis presented that was specially designed","kit-publication-id":"220071097"}]